1. Field of Invention
The present invention relates to a pump; and more particularly to a pump having an impeller with front and back sides.
2. Description of Related Art
In a typical centrifugal pump, fluid is accelerated through centrifugal forces exerted on it by an impeller. An impeller is a rotating disk driven by a motor whose front side has vanes extruding from it, which are used to transmit energy to the fluid being pumped. The rear or back side of the impeller is usually made as smooth as possible in order to reduce friction losses caused by the disk's rotation in the fluid being pumped. However, some shortcoming related to an impeller having a smooth rear or back side include the fact that debris can collect near the shaft seal and possibly cause pump jamming and failure of the shaft seal. Debris can also jam in between the backside of the impeller and the motor housing and cause the pump to lock up.
U.S. Pat. No. 5,489,187, entitled, “Impeller Pump With Vaned Backplate for Clearing Debris”, discloses a set of stationary vanes added to the backplate of a seal chamber in a centrifugal pump to help clear the area of the seal chamber of entrained air bubbles and debris using the fluid motion created by the impeller. The '187 patent also discloses vanes on the back side of the impeller as a means to encourage the flow which runs over the stationary vanes. However, some shortcoming related to '187 impeller design include the fact that it relies on complex flow patterns to achieve its purpose. These patterns may be difficult and time consuming to predict and may vary from pump to pump. Also, the construction is composed of rotating and stationary vanes and debris can possibly get wedged between these two vanes and jam up the pump.
See also U.S. Pat. No. 5,019,136, which discloses a pump including an impeller having a backside with either rear straight radial vanes, or rear straight inclined vanes that are inclined rearwardly relative to the direction of rotation, or rear curved longer and shorter vanes curved rearwardly relative to the direction of rotation, or a combination of rear curved longer and shorter vanes curved rearwardly relative to the direction of rotation, e.g., also having gas discharge openings.
See also US 2012/0051897, which discloses a pump having a combination of a suction liner and an impeller, where the suction liner has curved vanes and the impeller has forward curved impeller suction side pump out vanes.
There is a need in the art for a pump having a better impeller design that overcomes the aforementioned problems with these known designs.